1. Field
The aspects of the disclosed embodiments relate to a machine tool and a workpiece machining method.
2. Brief Description of Related Developments
It has been known to machine workpieces by cutting using tools with defined cutting edges. The best known methods in this connection are drilling, turning, milling and planing. The associated tools have one or several distinctively defined, clearly describable cutting edges. Machining is performed by a relative motion between tool, in particular its cutting edge, and workpiece (cutting motion). It is performed involving a particular removal rate and a certain tool wear and produces surfaces of—to a certain extent—predictable characteristics. In the drilling process, as a rule, the tool is moved, in the turning process the workpiece is moved. In the milling process, as a rule, the milling tool rotates while it is displaced, or the workpiece itself is displaced. In the planing process, the tool or the workpiece can be displaced.
It has furthermore been known to machine workpieces by means of vibrating tools without defined cutting edges. The vibrating tools are rough, they work by grinding and vibrate at comparatively high frequencies (vibration motion), e.g. at frequencies above 5 kHz or above 10 kHz or above 20 kHz. Because of the high vibration frequencies, which can lie beyond human hearing range, the processing is often termed as ultrasonic machining, and the machine is called ultrasonic machine. The vibration of the tool can be a translatory or a rotatory vibration. The tool can move parallel to the surface along the workpiece and remove material in a quasi filing way. It can, however, also act upon the workpiece by hammering (vertically to its surface).
A disadvantage of the known machining methods using tools with defined cutting edges is that in certain machining situations, in particular in the case of specific workpiece materials, the removal rate is relatively low or the tool wear is relatively high or the surface quality of the workpiece to be machined is relatively poor. It becomes apparent that the breaking-out of chips when machining with conventional tools having defined cutting edges produces comparatively rough and chipped surfaces which are not optimally mechanically resistant and are sensitive to environmental influences (corrosion, rust).
A further disadvantage is that the workpiece surfaces are often only insufficiently adapted to use specifications of the workpiece with regard to their fine structures, and are either used in this state or must be reworked.